There are several ranks in the game that you would reach as you earn points from online races. When you win an online race you would get 10 points, if you finish 2nd you would get 7 points. So you may have an idea about the ranks and how easy/difficult to reach them in the game.

Amateur -
Beginner - 200 points
Expert - 1000 points
Semi Pro - 5000 points
Pro Levels - 10000+ points

There are 19 multiplayer achievements in total. Some of them easy, some of them extremely challenging. You can find theme here:

My Challenge to The World
Play your first Online race


Eat my Dust
Win your first Online race


I'm Warming Up
Win 5 Online races


Don't Stop Me Now
Win 25 Online races


I am legend
Win 50 Online races


The Road is my Kingdom
Win 100 Online races


Learner
Achieve Amateur Rank


Driving Licence
Achieve Expert Rank


We're Starting to Get Serious
Achieve Semi-Pro Rank


A True Racer
Achieve Pro 1 Rank


The Essence of the Track
Achieve Pro 2 Rank


Made of Pistons
Achieve Pro 3 Rank


I also Drive When I Sleep
Achieve Pro 4 Rank


The Engine is My Music
Achieve Pro 5 Rank


Light Head and Heavy Foot
Achieve Pro 6 Rank


Steering Wheel Wizard
Achieve Pro 7 Rank


I See the Summit
Achieve Pro 8 Rank


No One is Faster Than Me
Achieve Pro 9 Rank


The God of the Racers
Achieve Pro 10 Rank

Super Arcade Racing is available on several platforms including mobile. Also the game doesn't require any log-in process.

So you can download the exact same game on your mobile phone or tablet and play it for free. Because the game is free on mobile, you will see some ads here and there, but it is not a big issue.

You need to play the story and finish the first 7 maps, then go to multiplayer and start searching for players. If no one is online, you can play it with yourself on both pc and your phone. Just finish the race and earn 10 points. You don't need to finish it on your phone.

If any other players online and looking for opponents to play with, you can create a room (Invite section) and join the room and play it easily.

Super Arcage Racing on IOS [apps.apple.com]

Super Arcage Racing on Android [play.google.com]

As you can see above, you need to win 100 online races if you wish 100% achievements. And still it wouldn't be enough because 100 wins gets you 1000 points and you will only get Expert. To be able to get pro ranks, you need to waste lots of time.

I think the highest rank should require ~1000 points so when you get 100 race win achievement you would get the highest rank possible. Since there are not many players to play with, there is no reason to make it so difficult and tame wasting to achieve.

And the ranks should go 0-200-400-600-800-1000 points to get. In this way it would be fun. There is no logic to put 10k+ points rank in a game with a couple of players.